<!DOCTYPE html>
<html>
<head>
	<meta charset="utf-8">
	<meta name="viewport" content="width=device-width, initial-scale=1">
	<title></title>
	<style type="text/css">
		*{
			margin: 0;
			padding: 0;
		}
		.box{
			width: 200px;
			height: 200px;
			background-color: red;
			animation:aa 5s 5s;
		}
		.one{
			width: 200px;
			height: 200px;
			background-color: blue;
			animation:aa 5s 5s;
			animation-fill-mode: backwards;
			/*forwards   停留在最后一阵
			backwards  先进入第一帧等待
			both       两者皆有*/
		}
		@keyframes aa{
			0%{
				width: 250px;
				background-color: orange;
			}
			100%{
				width: 500px;
				background-color: skyblue;
			}
		}


	</style>
</head>
<body>

	<div class="box"></div>
	<div class="one"></div>





</body>
</html>